Inertia operated switch



JDEZZANI 2,216,364

INERTIA OPERATED SWITCH Filed Nov. 9. 1956 INVENTOR ATTORNEY Patented Oct. 1, 1940 UNITED STATES PATENT OFFICE 3 Claims.

Heretofore in automobile operation we have known of no other means of signalling to a following motorist other than by hand signals or by stop lights which work only when the brakes are applied. Manifestly it is not safe to depend on hand signals as many drivers fail to use them correctly and some do not use them regularly. While hand signals can be readily seen in daylight driving, at night or in a fog the hand signal is almost useless, Stop lights are almost always operated only when the brakes are applied and in most cases they are hard to distinguish from the ordinary tail lights.

The purpose of my invention is to provide a device which is entirely independent of the driver or the brakes, and one which will give its warning to the following driver whenever the car ahead slows down even to a small degree. A further purpose is to provide a device which is wholly automatic and one which also indicates the rate of deceleration, that is, one which will produce a faint signal for a slight deceleration of the leading car, or a brilliant signal for a sudden stop. Another purpose of my invention is to provide a means of producing a more brilliant signal with a marked reduction in battery drain.

I accomplish these purposes of my invention by means of the mechanisms illustrated in the accompanying drawing, in which similar numerals refer to similar parts in the several views.

The drawing shows a preferred type of mechanism and is shown diagrammatically with the cylinders and case in vertical central section. The drawing also shows the device when there is no deceleration.

The construction of my device as shown is as follows: II is a box or housing which contains all of the mechanism except the signal light, and which is mounted at any convenient place on the vehicle. Mounted within the housing I I and insulated therefrom is a chamber I2 adapted to contain mercury, and secured to this chamber I2 is a relatively large upright cylinder I3, preferably of glass, and also another upright glass cylinder I4 of asmaller diameter; the chamber I2 and both of the said cylinders are adapted to contain mercury and filled to a definite level, the mercury being free to flow from one cylinder to the other through the chamber I 2. In the larger cylinder I3 is a piston I5 having a piston rod I5 extending upwardly through the cover of the said cylinder. The upper part of the said piston-rod has rack teeth out therein. Adapted to mesh in the rack I! is a segmental gear I8 which is rotatably mounted in the housing I I, but insulated therefrom. Secured to the gear I8 or to its shaft I9 is a pendulum weight 20, adapted to swing forwardly or backwardly as it is acted upon by the acceleration or deceleration of the vehicle, and in so swinging adapted to actuate the rack I I and the piston I5. In the center of the piston I5 is a port 2I which allows mercury to flow from one side of the said piston to the other side, but being of small diameter it restricts the tendency to sudden movements of the piston, acting as a I damper. This part also allows any mercury which has been forced above the piston, to again seek its level. Located at the bottom of the cylinder I3 is a stationary stopper 22 which will fill the port 2| should the piston descend suificiently,

and for a purpose which will be more fully hereinafter described. Embedded in the wall of the upper part of the cylinder I4 are a series of electrical contact points 23, each of these points being connected to one unit of a bank of resistors 24. These resistors are wired in parallel with one side of the battery 25, the other side being grounded. Another electric lead 26 is connected between the mercury in the cylinders and a half or full-wave vibrator 21 and a transformer 28. I

The operation of this type of my invention is as follows: It is assumed that the vehicle is traveling in the direction of the arrow 30, and that the pendulum weight 20 is so mounted on the vehicle that it can swing only in a direction parallel to that in which the vehicle is traveling. When the vehicle is in motion at a practically uniform speed, or when it is standing still, the pendulum will assume the position shown. If acceleration takes place the pendulum will move further backwardly, raising the piston I5 and lowering the level of the mercury in the cylinder I4. When deceleration in the speed of the vehicle takes place the pendulum 20, due to its inertia, swings forwardly depressing the piston I5 and forcing the mercury level in the cylinder I3 downwardly and causing it to flow through the chamber I2 and raising the level of the mercury in the smaller cylinder l4 and causing contacts to be made between the mercury and one or more of the resistor points 23, which are molded in the glass wall of the cylinder M or otherwise insulated from each other. A continuous contact is maintained between the mercury and the lead 26. The contact points 23 being connected to resistors in parallel, and to the battery 26, current flows from the said battery through the resistors 24, the mercury, and by means of the connection 26 to a half or full-wave vibrator 21 and the transformer 28. Connected to the secondary of the transformer 28 is a gas-filled lamp or an incandescent lamp. This lamp is the stop light and should be mounted on the rear of the vehicle where it can be plainly seen by a following motorist.

An important feature of my invention is the fact that the degree of brilliancy of the lamp is proportional to the rapidity of the deceleration. The more sudden or intense the deceleration the more the swing of the pendulum weight 20 the greater the piston pressure on the mercury, the greater the rise of the mercury in the cylinder 14 and the greater number of contacts between the contact-points 23 and the mercury are made. This cuts in more resistor units 24 and allows a greater flow of current and a higher A. C. voltage to the lamp, increasing its brilliancy.

The size of the port 21 in the piston I5 can be calibrated so as to provide for a definite time constant in the operation of the device. In this way a definite degree of lamp or signal brilliancy can be obtained for any given rate of deceleration. If the port 2| is over-size, the mercury would travel through the port so quickly that there would not be any appreciable rise of the mercury in the small cylinder [4 and consequently little or no brilliancy in the lamp. On the other hand, if the port 2| be too small the resistance to the flow of mercury through the port would be so retarded that any deceleration would result in instant and considerable rise in the small cylinder and there would be intense brilliancy in the signal for even a slight amount of deceleration. The ideal condition will be a port 21 of a size suitable to produce a variable brililancy directly proportional to the intensity of the deceleration.

In an extremely rapid deceleration the piston l5 rapidly descends until the stopper 22 enters the port 2| of the piston, thus stopping the fiow of mercury through the said port and resulting in a rapid and heavier flow of mercury into the cylinder l4, cutting in all of the contacts 23 and producing a light of maximum brilliancy. The stopper 22 being a very close fit in the piston port 2!, little or no mercury can leak through the piston, thus holding the mercury in contact until the vehicle stops. By having the cylinder [4 of a smaller diameter than the cylinder [3 the mercury displaced by the depression of the piston 15 rises to a higher level in the smaller cylinder, resulting in a saving in the amount of mercury required. The

nected with the lower part of the said primary cylinder, and both cylinders partially filled with mercury; a pair of electrical contacts in said secondary cylinder normally insulated from each other but adapted to be connected by the rise of mercury in said secondary cylinder when the said piston is depressed.

2. In an inertia operated switch the combination of a pendulum weight adapted to be actuated by the deceleration or acceleration of the said switch as a whole; a primary cylinder having a piston and piston-rod therein; means for actuating said piston and piston-rod, saidmeans consisting of a segmental gear on said pendulum weight adapted to engage rack teeth on said piston-rod; a secondary cylinder connected with the lower part of the said primary cylinder and both cylinders partially filled with mercury; a pair of electrical contacts in said secondary cylinder normally insulated from each other but adapted to be connected by the rise of mercury in the said secondary cylinder when the said piston is depressed; means for damping the movement of the said piston, said means consisting of a by-pass port through the said piston.

3. In an inertia operated switch the combination of a pendulum weight adapted to be actuated by the deceleration or acceleration of the said switch as a whole; a primary cylinder having a piston and piston-rod therein; means for actuating said piston and piston-rod, said means consisting of a segmental gear on the said pendulum weight adapted to engage rack teeth on said piston-rod; a secondary cylinder connected with the lower part of the said primary cylinder and both cylinders partially filled with mercury; a pair of electrical contacts in said secondary cylinder normally insulated from each other but adapted to be connected by the rise of the mercury in the said secondary cylinder when the said piston is depressed; means for damping the movement of the said piston, said means consisting of a by-passport through the said piston; and means for increasing the rapidity of mercury fiow from the primary cylinder to the secondary cylinder, said means consisting of a stopper adapted to enter and close the said piston port in case of an extreme and sudden deceleration of the vehicle and consequent sudden depression of the piston.

JOHN DEZZANI. 

